1. In a large nonstick frying pan, melt the butter over moderate heat. Sprinkle the sole with 1/2 teaspoon of the salt and the pepper. Dust the sole with the flour and shake off any excess. Put the sole in the pan and cook for 2 minutes. Turn and cook until just done, about 2 minutes longer. Remove the sole from the pan.
2. Add the cream and lemon zest to the pan. Bring to a simmer and cook until starting to thicken, about 2 minutes. Stir in the remaining 1/4 teaspoon salt, the lemon juice, and parsley. Serve the sauce over the fish.
Fish Alternatives: Other members of the flounder family, such as sand dab or fluke, will go well with the sauce, as will such mild fish fillets as trout, hake, or whiting.
Wine Recommendation: A ripe, full-flavored chardonnay with oak overtones will be well suited to the richness of this creamy dish. Try a bottle from California or Australia.